The present invention relates to an image display device and a light emission device, more particularly to an image display device of a small size with high performance and high reliability and a light emission device which is suitable for various kinds of uses including a light source of the image display device.
An image display device plays a role as an interface that visually connect various kinds of electrical equipment and human beings. In the present information society, the role of image display devices is essential, and the image display device is a key component in a wide field that includes television sets, computers, information terminals, game machines and household electronic appliances. At the same time, development of new high performance image display devices is desired to meet the needs of the present information society as it rapidly develops and increases in diversity.
For such image displaying devices, a Braun tube and a liquid crystal display device have been mainly used. The Braun tube scans an electron beam in a glass tube sealed to produce a vacuum and excites fluorescent bodies arranged on a shadow mask, thereby displaying an image. The Braun tube can be manufactured relatively low in cost, and is capable of displaying high quality images. Therefore, in general, the Braun tube is widely used as an image display device for television sets, computer monitors, etc.
On the other hand, a liquid crystal display device applies a designated electric field to a liquid crystal layer held between two substrates, thereby changing an optical property of the liquid crystal layer to display changes of intensities of transmitted light and reflected light in the form of a predetermined image. When the liquid crystal display device is compared with the Braun tube, the liquid crystal display device has an advantage that it is thin in thickness and light in weight. Liquid crystal display devices are used in electronic equipment such as notebook computers and various kinds of portable information console units.
With the development of the foregoing electronic equipment and the advancement of the information society, image display devices must be made smaller in size, lighter in weight, and display an image with higher quality and reliability.
However, the Braun tube has structural problems because it is large in length in its tube direction, heavy in weight, and since it is a vacuum glass tube, it has an insufficient durability against vibrations and shocks.
On the other hand, a conventional liquid crystal display device uses a cathode fluorescent tube as its light source, which meets manufacturers needs for a small-sized, thin cathode fluorescent tube having long life, in addition to having display luminance. However, there is a problem in liquid crystal display devices, that the visual field angle is narrower than that of the Braun tube, so that image recognition from an oblique direction is significantly poor.
The present invention was made from the viewpoint of the above described circumstances. Specifically, the object of the present invention is to provide an image display device which is easy to manufacture, small in size, light in weight, having has a wide visual filed angle, capable of displaying a high quality image, and having a high reliability, and to provide a light emission device which is suitably used for a light source of such image display device and for other various kinds of uses.